Removal of nitrogen compounds from hydrocarbon oils by adsorption on cracking catalyst



3,189,539 OM HYDROCARBON ING CATALYST ay 14, 1962 June 15, 1965 R. P. SIEG OGE N COMPOUNDS FR PTION ON CRACK Filed M REMOVAL OF NITR OILS BY ADSOR United States Patent n lig Patented .inne l5, 1965 REP/IQVAL 0F NETRUGEN CGMPUNDS FRM HYDRGCARBGN @iid BY ADSGRPHN 9N CRAClQNG CATALYS' Robert P. Sieg, Piedmont, Calif., assigner to California Fiese rch Corporation, San Francisco, Caiir'., a corporation of Delaware Filed May 14, $62, Ser. No. 194,254 2 Claims. (Ci. 20S- 254) 'Ihis invention relates to processes for the removal of contaminating nitrogen compounds from hydrocarbon oils. More particularly, the invention relates to processes for the removal of nitrogen compounds from a hydrocarbon oil by adsorption of the nitrogen compounds on a cracking catalyst.

In one embodiment the invention comprises a combination of a catalytic cracking process and a catalytic hydrogenation process, wherein nitrogen compounds are removed from the feed to the catalytic hydrogenation process by adsorption on a slip stream of regenerated catalyst from the catalytic cracking process.

The removal of contaminating nitrogen compounds from a hydrocarbon oil is known to improve the properties of the oil in many respects. For example, the color is usually improved, thereby enhancing the market value of a salable oil. Also the oil is made more amenable to further processing such as catalytic reforming, hydrocracking, and hydrogenation. It is especially desirable to reduce the nitrogen content of a hydrocarbon oil to a very low value to prepare a feed for an acidic catalytic hydrocrachng process. The lower the nitrogen content of the oil, the lower the temperature and pressure which may be employed in the hydrocracking process and the longer the catalytic life will be.

lt is known that nitrogen compounds can be removed from oils by adsorption on solid contact agents. However, previous attempts to accomplish substantial denitriication by selective adsorption have proved to be uneconomic for various reasons. In processes heretofore proposed the loss of valuable hydrocarbons adsorbed or entrained with the nitrogen compounds on the adsorbent has been excessive. The cost of cyclic processes wherein it is attempted to recover these hydrocarbons from the adsorbent by elution or chemical treatment has been excessive, and adsorbent life has been unsatisfactorily short. Y

lt is an object of this invention to provide a process for the removal of nitrogen compounds from hydrocarbon oils by adsorption wherein there is little or no loss of hydrocarbon oil, which process is inexpensive to operate, and which uses a rugged, low cost, adsorbent.

Another object is to provide a combination of a catalytic cracking process and an adsorption process, Wherein cracking catalyst is used both to crack hydrocarbon oils in the cracking process and to denim'fy another hydrocarbon oil in the adsorption process, and the cracking process provides the means for removing the adsorbed nitrogen compounds from the catalyst, without adversely afecting the operation of the cracking process.

Another object is to supplement catalytic hydrogenation processes for the removal of nitrogen compounds from a hydrocarbon oil by removing a substantial portion of the nitrogen compounds from the oil by adsorbing them on a portion of cracking catalyst withdrawn from a catalytic cracking process, and then reusing the catalyst for cracking other oils. Y Y

In accordance with the invention nitrogen compounds are removed from a hydrocarbon oil by adsorbing said compounds on a solid adsorbent, using as the adsorbent a minor portion of freshly regenerated cracking catalyst withdrawn from a catalytic cracking process having a reaction zone and a regeneration zone between which the catalyst is continuously circulated, and returning Vthe catalyst having nitrogen compounds adsorbed thereon to the catalytic cracking process. The hydrocarbon oil treated should boil below about 750 F., or it should contain below Vabout 200 ppm. nitrogen initially. Preferably, the feed is restricted with respect to both of these factors.

In this Way the catalytic cracking process provides the sole means for removing adsorbed nitrogen compounds from the adsorbent and for providing adsorbent free of nitrogen compounds to the adsorption step. Hence, the nitrogen removal is very economically accomplished because a continuous noncyclic process can be used and there is no need to provide separate facilities for adsorbent elution or regeneration. Since only a minor portion of the cracking catalyst is involved, generally less than 5% of the circulating catalyst, the operation of the catalytic cracking process is not adversely atiected. The cracking catalyst is known to be very rugged, and it is a good adsorbent for nitrogen compounds.

The process of this invention comprises the steps: (l) withdrawing a portion of freshly regenerated cracking catalyst from a catalytic cracking process, (2) contacting a liquid hydrocarbon oil containing nitrogen compounds with said portion of regenerated cracking catalyst at conditions at which a substantial portion of the nitrogen compounds isadsorbed on the catalyst, (3) separating the catalyst carrying adsorbed nitrogen compounds from catalyst-free oil reduced in nitrogen content, (4) returning said catalyst to said catalytic cracking process, and (5) recovering said catalyst-free oil reduced in nitrogen content.

in a preferred embodiment, after contacting the oil and the catalyst, a slurry of oil and catalyst carrying adsorbed nitrogen compounds is separated from catalystree oil reduced in nitrogen content. This oil-catalyst slurry is returned to the reaction zone `of the catalytic cracking process. rl`he oil entrained withY or adsorbed on the cracking catalyst is thereby recovered by cracking to valuable products in the catalytic cracking process. The catalyst-free oil reduced in nitrogen content is passed to a catalytic hydrogenation zone wherein additional nitrogen compounds are removed by hydrogenation to ammonia, and/or hydrocarbons contained in the catalystfree od are hydrocracked to lower-boiling hydrocarbons.

The attached drawing is a block flow diagram illustrating certain preferred embodiments of the invention. Reference thereto will also be helpful in explaining the basic features of the invention. A v

Referring to the diagram, there is shown a catalytic cracking process of conventional design, comprising a catalytic cracking reaction zone 2 and a catalyst regeneration zone 7. Operating conditions and equipment used in the reaction zone and regeneration zone are well known, and need not be reiterated here as the conditions are not noticeably altered by the practice of this invention. Catalyst is continuously circulated between the reaction zone and the regeneration zone by passing spent catalyst from the reaction zone to the regeneration zone through line 6 and by passing regenerated catalyst through line S back to the reaction zone. As shown, the regenerated catalyst is usually returned to the reaction zone in admixture with the hydrocarbon oil feed to the catalytic cracking process in line i. Usually, there are several product streams recovered from the catalytic cracking reaction zone, including light gases, represented by line 3; gasoline, represented by line 4; and one or more cracked cycle oils, represented by line S.

Any suitable active cracking catalysts may be employed best results in the then mix forming a slurry in line 12 fphese. Y f Y Y, u The adsorption is carried ,out at conditions Vatuwbich 'a A v d l in theV Vcatalytic craclringrprocess. VUsually a synthetlc silica-alumina, an acid activated'clay catalyst, or a 'silica-1 The catalyst may be in the powdered or iiuidizable size Yrange and` be circulatedV by magnesia composite is used. j

means ofliitrgases such vastherregener'ation airV and the hydrocarbonroil feed. Alternately, "the therrnoior type f o Vcatalytic cracking may be employedwhereinr a catmy'st of larger dimensions is mechanically Yconveyed'between the reaction zoneand'the regeneration zone. VVFor Y i practice ofV this invention it is preferred to'use arsilrica-alumina crackingcatalyst. Y

i in accordance ,with the invention a minor portion Vof the freshly regenerated cracking catalyst in line Sisrwithdravvn through line l1. Y This Withdrawn portion of /catalyst-isused as the adsorbent to remove`contaminating Y nitrogen compounds from a liquid hydrocarbon oil. For

line 9 and passed through line it). The oil and catalyst and pass to separation zone 1.3.Y Suitable Vconditions for adsorption are achieved Vadsense A catalytic cracking process, for

Y' ing with the hydrocarbon oil feed to the vcracking process in line 1. The entrained oil and the adsorbed nitrogen compounds arethen converted to hydrocarbonV products `andY recoveredrin lines 3,'l-or 5. Y Y n A y ItV is also possible toV return thecatalyst 4carrying adin the reaction zone of Ythe catalyticfcracking process,

Y Y sorbed nitrogen compounds Yto the regeneration zone of the catalytic-cracking process throughline 2S rather than y Then, however, to minimize the hydrocarbons,l the catalyst Vshould Vbe Vseparated from the catalyst-free oil iny separation zone Y to the reaction zone.

loss of valuable 13 by ltrationror an'requivalent methodfwhich provides Ya substantially dry catalyst'rather than a'slurr'ysv "lny accordance VwithV a Vpreferred' embodiment jofV the l invention the recovered catalyst-free oil reduced nitro- VVexample, such a hydrocarbon oil'is introduced through Y,

'in line lZKVand maintained in separauon zone l whereby f a substantialportion ofthejnitrogen compounds initiallyV contained in theliquid hydrocarbon oil is adsorbed ou 'the'catalyst contacting of the oil andthe catalyst for a suiicient time for adsorption of at least 10%0f the nitrogenV corupounds, at a temperature at which the oil is in the liquid crackingV does not occur, andthere is not other-chemical 'conversion of the oil or constituents therein Yto any Ysignifi-Y cant extent. Regenerated 'catalyst in line S is normally at a temperature of aboutV 1090-1100 The portion of catalyst withdrawn in line 11 should be cooled to be- `low the-temperature at which Vcracking would occurron contacting the oil Vin line i2, ie., below about '989 F. Suicient cooling may be accomplished, for example,

by heat lossesrto the-atmosphere in line l1', by providing The conditions should provide torV intimate' for 'intermediate storage in line il, orV by using a relatively cool inert gas to rnove thecatalyst (if of uidizabie size) through line il. The'quenching eiect ofV contact with the Ynitrogen-containing oil in lineV 12 further adjusts the temperatureV to the desiredrange. Best results are 408y F. The adsorption is quite Vrapid initially, and consequently the bulk of theadsorption occurs in the i'irst few minutes of contacting. The average contacting time Y Y'obtained if thetemperature is maintained below Vabout need not exceed Vabout one hour, including the separation Y.

time.'

. The ratio of catalyst to oil selected depends Vto some extent on the properties of the oil, such as its Vboiling point and itsV initialnitrogen-content. However, I have found that, when using as the adsorbent@Y cracking catalyst inaccorda'nceY with this invention, the bull; of theV j-,adsorbable' nitrogen compounds can be Yadsorbed using Y aV Weight ratio oi catalyst to 4oilV of less than about 0.1.

VThe useof alow catalyst-to-oil ratio is especially preferred because the cost'of moving the catalyst adsorbent is there- .by"minirni'zed, the separation of oil vandv catalyst is f simplified, and ahigher yield Yof oil reduced in nitrogen content is obtained. Y

YThe catalyst having nitrogen compounds adsorbed thereon is separated 'from the Vresulting catalyst-free oilV reduced in nitrogen contentV in `separation zone'3. Liquidhydrocarbon oil reduced in nitrogen content is` re- Ycovered from separation zone l'rin line 15. Therseparation may be accomplished inV any'of several known ways,

including filtration, simple-,settling in a vessel or pond,

Yor under the inuence of 'centrifugalf'force In ja pre..-

ferred embodiment, preferably a slurry of'oil and catalystk carrying adsorbed nitrogen compoundsV is separated from oil by,4 settling, and thel oil-catthe catalytic crackingprocess,

the'A resulting catalyst-free Valyst slurry is returned to- 1 for example, by pumping through line 14. Most advanthe reaction zone ofthe Y tageously the slur/ry is returned to Vgen content, in line 1:5,V

gen compounds VareV removed .byV hydrogenationV toA arnmonia.

compounds have alreadyV been removed from the' oil, Vit is found thatr the vremaining nitrogen lcompounds are much moreV readily converted to ammonia by catalytic hydrogenation. Y with aA sulfactive hydrogenation catalyst at elevated tem-V perature and pressure and in Y genin a known manner.

contactedV With a cobalt-molybdate or .nicliel` Ysulticle- Y molybdenum sulfide or' other catalyst Vcomprising one` or Y v Amore oxidesV or suhides of metals ofl groups VI and VIII ofthe periodic'table supported-on a carrier, suchrras alumina, at a liquid hourly space velocity of'tlZ--VISl LHsv, 50o90c7- F., 2ooe5ose 1p.s,i.grand in the presi-1, ence of 1009-1106()V cubic feet of hydrogen 'per barrel of I oil. Nitrogen-,free oil is recovered in line-17.

I have foundthatk the removal of nitrogenV compounds 'f 'by' adsorption o n crackingcatalys'tsis most efiicientif the Y oil has only afrnoderatelyhigh initial 'nitrogen content,

preferably less than aboutZO ppm."nitrogen.V VAccord- Y ingly, Vit the nitrogen contentV is higher, in aprerferredfern-YV bodiment'the o'il'rin'line 9 Vis passed throughline-26de'V Vcatalytic::hydrogenationV zone 23. In Zone 23 the saine Y types of 'catalysts andoperatingconditions may be Yemployedzas previously described ufor zone 16. Vlelydrocar- -bonv oil reduced in Vnitrogen content is recoveredtroi'nVV zone 23 in line 24. TheV oil then passes `through linel to mix with the portionV of'regenerated cracking catalystYV vin line lll,r forming an'intimate mixture-in line 12'Which' e .then passes'to separation zoneV 13. Hydrocarbon oilifur- Yther reduced in 'nitrogen rcontent is recoveredin'line 15.Y When this material is processed in catalytic Vhydrogena- Ation zone 1'6 it isY ,foundy that the rate at which the'nitro-` .gen compounds convert to ammonia at typical operatin`g'-.V conditions Vof'700" 1Hand Vl100'p .s.i.a; hydrogenpartial .pressure is much greater tha'nQtheV reaction rate at the same conditions in zone23. For example, afterremov- .ing about 90% of the nitrogen compounds bycatalytic hydrogenationin zone 23, and then removingrlan addil Y Vtional 40% of the remaining nitrogen compoundsby con- .tacting in lineV i2 and separating in zone.lxathereactionV Vrate infzone le is nearly five times as rapid asth'e reac-`r tion ratein zone 23 at the-same conditions. 4The oil in line 15 isrthus very easily purified to remove substantially-'YV all of the nitrogen compounds therein to produce a nitro;VV

.gen-free oiljin line 1'7. The nitrogenfree oilcan then be passed-to catalytic'hydrocracking zone'lS VWhereinthe Yoil is hydrocracked to Ylower boiling hydrocarbon ,prod-r ucts. VThe products' usually include aV gaseous portion recoveredfin line 19, alight Yliquid productr'recoveredin f line Ztl, andk a heavier liquidproduct recovered in lineZl. In' hydrocracking zone V1t; the nitrogen-freeoiliis con'- vtacted with a catalyst comprising a hydroger'ration-dehy-V drogenation component supportedA on a refractory oxide Vsupport having cracking activity. Zone Ed isV operated' atY conditions causingV a signiiicantnet consumptiou'of hydro-V example as shown, by mix- :s ypassed to a ,catalyticV hyclro-V Y genation zone,'suc'n Vas zone 15, wherein additional nitro-f Because va substantial portion ofV theY nitrogen f `YIn zone 1.6 thefoiLmay beV contacted.;Y

the presenceof excess hydro-V 'Y Specifically, the VYoil maybe gen in excess of 500 standard cubic feet per barrel. Hence, it may also be termed a catalytic hydrogenation zone. With an essentially nitrogen-free oil inline 17, i.e., below l0 ppm. nitrogen, it is preferred to use an acidic hydrocracking catalyst such as cobalt or nickel suliide supported on a cracking catalyst such as silica-alumina. Low temperatures of 50G-800 F. may then be employed at pressures of 100G-3000 p.s.i.g. and space velocities of 0.3- volumes of oil per volume of catalyst per hour in the presence of 100G-15,000 s.c.f. of H2 per barrel. With a higher nitrogen content in the oil, somewhat higher temperatures of 700-850 are employed in zone 18. A satisfactorily low nitrogen content of 10-100 ppm. may be achieved in the oil in line 15. In that case it is often more economical to bypass zone 16 by passing the oil through line 22 directly to Zone 1S.

With an acidic hydrocracking catalyst in zone 18 the oil feed in line 17 or line 22 tends Vto be hydrocracked predominantly to gasoline boiling range products. If it is desired to maximize middle distillate products, a catalyst of lesser acidity or a nonacidic Catalytic hydrogenation zone i6 ordinarily employs a nonaciclic catalyst. Accordingly, zone 16 may be operated under conditions at which hydrocarbons contained in the oil feed in line 1S are hydrocracked to lower boiling hydrocarbons. All or a portion of the cracked products may then be recovered inline 27.

I have found that the removal of nitrogen compounds from liquid hydrocarbon oil by adsorption on cracking catalyst is most efticient as applied to only moderately high boiling oils, i.e., those boiling below about 750 F. Accordingly, a preferred feed stock is the light cycle oil product of the catalytic cracking process recovered in line 5. As shown in the diagram, all or a portion of the cycle oil may be passed through line 25 for contacting in line 12 with the portion of regenerated cracking catalyst withdrawn through line 1l. In accordance with a preferred embodiment of the invention all ora portion of the cycle oil in line 5 is passed via line 29 through catalytic hydrogenation zone 23 wherein a major portion of the nitrogen compounds contained in the cycle oil is removed by hydrogenation to ammonia. From zone 23 there is recovered in line 24 liquid hydrogenated oil reduced in nitrogen content. This oil passes through line 19 and is contacted in line 12 with the portion of freshly regenerated cracking catalyst withdrawn from the catalytic cracking process through line 11. In zone 13 a slurry of oil and catalyst carrying adsorbed nitrogen compounds is separated from the resulting catalyst-free oil and returned via line 14 to the reaction zone of the catalytic cracking process. There, the oil entrained with or adsorbed on the catalyst is more readily cracked to valuable products because it has been upgraded in quality as a cracker feed by the catalytic hydrogenation accomplished in zone 23. The catalyst-free oil further reduced in nitrogen content is separated in zone 13 and passed through line 15 to catalytic hydrogenation zone 16 where the remaining nitrogen compounds are easily substantially completely removed by hydrogenation to ammonia. The nitrogen-free oil so obtained is then passed through line 17 to catalytic hydrocracking zone 18 wherein the oil is hydrocraclied to lower boiling hydrocarbon products 19, 2B, and 21.

The following examples illustrate the use of regenerated cracking catalyst to adsorb nitrogen compounds from liquid hydrocarbon oils and the importance of certain of the aforementioned preferred features in the contacting step. The first example illustrates the removal of nitrogen compounds from a catalytic cracker light cycle oil product using regenerated cracking catalyst as the adsorbent.

Example I I A light cycle oil having a gravity of 24.l degrees API, boiling from 383 to 647 F., and containing 1260 ppm. nitrogen, was contacted by mixing with regenerated.

catalyst is employed..

recovered in lines equilibrium, tluidized bed catalytic cracker silica-alumina catalyst at 300 F. The catalyst analyzed 81% SiO2 and 18.6% A1203 and had a surface area of 123 M2/ gm. and a pore volume of 0.35 cc./gm. After one hour of contacting, the supernatant oil separated from the settled catalyst-oil slurry was found to contain 965 ppm. nitrogen. Thus, about 23% of the nitrogen compounds were adsorbed on the cracking catalyst.

The second example shows that the adsorption is much more eicient with a feed having a lower nitrogen content.

'Example Il The light cycle oil feed of Example I was catalytically hydrogenated to remove the bulk of the nitrogen cornpounds by conversion to ammonia, and the nitrogen content of the product `was then adjusted'to 133 p.p.m. by blending with a small portion of unhydrogenated cycle oil. The cycle oil reduced in nitrogen content to 133 ppm. was contacted with a portion of the regenerated silica-alumina catalyst at 300 F. at a weight ratio of catalyst to oil or" 0.05. After one hour the supernatant catalyst-free oil was found to contain only 83 p.p.m. nitrogen. Thus, about 38% of the nitrogen compounds initially contained in the oil were adsorbed on the cracking catalyst even though a much lower ratio of catalyst to oil was used as compared to Example I. Moreover, there were more moles of nitrogen compounds adsorbed per unit weight of catalyst in this example than in Example I; about 25 mg. of N per grain of catalyst as compared to about 16.3 ing/gm.

The following example uses a longer contact time, showing that a short contact time of not more than about one hour is adequate to accomplish the bulk of the adsorption.

Example III A portion of the light cycle oil containing 133 ppm. nitrogen was contacted with the regenerated cracking catalyst at 300 F. and a weight ratio of catalyst to oil of 0.05. After three and one-half hours the supernatant catalyst-free oil was found to contain 74 ppm. nitrogen. Thus, about 44% of the nitrogen compounds were adsorbed on the catalyst, representing the removal of only 6% more of the nitrogen compounds than in Example ll, but in three and one-half times as much time.

The following example of treating a higher boiling feed shows that the process .of this invention is most etiicient for the removal of nitrogen compounds from only moderately high boiling hydrocarbon oils.

Example I V A heavy cycle oil having a gravity of 24.6 degrees API, boiling from 561 to 845 F., and containing ll95 ppm. nitrogen was catalytically hydrogenated to remove the bulk of the nitrogen compounds by conversion to ammonia, and the nitrogen content of the oil was then adjusted to ppm. by blending with a small portion of the unhydrogenated oil. The oil containing 150 ppm. nitrogen was contacted with the regenerated silica-alumina cracking catalyst at 300 F. at a catalystto-oil ratio of 0.05, After one hour the catalyst free supernatant oil was found to contain l2l ppm. nitrogen. Thus, only about 20% of the-nitrogen compounds in the heavy cycle oil were adsorbed on the catalyst wh reas, at the same treating conditions, nearly 40% of the nitrogen compounds were removed from the light cycle oil, in Example il.

The following example with a higher catalyst-to-oil ratio shows that the use of a low catalyst-to-oil ratio of less than about 0.1 is most eicient in the practice of this invention.

Example V A portion of the heavy cycle oil containing 150 ppm. nitrogen was contacted with the regenerated cracking temperature.

' invention, but with Y greater Y plete removal ofthe manner. Y

. catalyst at 300 r. ata catalyst-to-oil ratio of 0.4i "After one hoar'the catalyst-free supernatant oil was found to contain 1:30 ppm. nitrogen. fhus, 33% of the nitrogen compounds were adsorbed on the catalyst as compared to 20% Vin Example IV, VbutV eight times as much catalystwas required per unit Weight ot oil.

Litho above examples, the regenerated cracking catalyst used as the adsorbent had been stabilized by Aoxidation at ll00 F. When tresh catalystsor old hydrated cata: lysts were used, adsorption was less eriicient, and the results were erratic and not reproducible with dii'erent batches ofl the same catalyst. Hence, it is important to use regenerated catalystl recentlyfwithdrawn from the cracking process. Y Y. f Y

lnot'nerftests at a contacingrtemperaturerof 400 F.,

the adsorption of nitrogen compounds on the silica-v alumina cracking catalyst was considerablyrless erective.

For example, only 10% of the nitrogen compounds were Y3,189,539VV adsorbed from thev heavy cycle oil at, conditionsk comparablek to Vthose Vof Example EV except for kthe treating Eest'res'ults` are lobtained Vat .near ambient temperature, i.e., 50-90o R, but some1 added expense iS then involved in cooling the regeneratedcra'cking catalyst before or during contacting with the oil. i

As described .with reference to the examples,the contactingY of the oil containing nitroj f gen corn-pounds with the portion of regenerated catalystv v,has beenreerred to generally as simpleVY mixing.

94% of the nitrogen compounds have been'removed from an oil oy adsorption than the preferred ratio of catalyst to oil and contact time. For more efcient utilization ot thecataly'st-adsorbent, or to obtain more comnitrogen compounds, several stages of contacting in series -could be used in a well-known Similarly,V `the oil and catalyst could be contheY diagram, and in Up toV in this way,v in the practice of the tacted in Yan nprightrrvessel or tower by Ytlowingthe oil fore returning it to the catalytic cracking reaction zone-Y o Wi.hout -departing'from the essential concept of using the catalytic cracking process to remove the adsorbed nitrogen compounds. 1I claim:A Y

1. A process for lowering the nitrogen content-optann .Y Voil'tromabove `200 p.p'.m'.'to below 10 p.p;m.,which I comprises:

,- (l) passing a hydrocarbon oil .containing yabove 200Y p.p.m. nitrogen in nitrogenjcornpounds Ythrough aVVV `rst catalytic hydrogenation'zone wherein a major portion of said nitrogen compounds is removed by hydrogenation to ammonia, and recovering liquid hydrogenated oil' boiling below about 750 Y reducedin nitrogen content tobelowijl()ppm.,V j

Y(2) contacting said liquid hydrogen'ated oil with a portion of freshly regenerated cracking catalyst with*-y Vdrawn from a catalyticcracking process, Vhaving/aV greaction zone and a regeneration Vzone between-which catalyst is continuously circulated, forming acatalystoil mixture at conditions including'a weightrratio ofV catalyst' to oil below 0.1', temperature below 400 F.; and ysufiicient contacttirne Vsuch'that at least.V 10% of the nitrogen compounds is adsorbed onthe` cata- Y lyst,V Y. Y V(3) separating catalytic cracking process,V (5) passing said 'catalystcatalytic hydrogenatmn zone'wherein', because vof Y the foregoing removal of nitrogen,compounds, the remaining nitrogen compounds are' substantially removed by` hydrogenationto ammonia morefeasilyVV than in saidtrst'hydrogenati'on zone, and recovering oil reduced lin'nitrogen content to below 10i-ppm'.

Y nitrogen. 2.

oil containing nitrogen-compounds is a light cycle foil recovered from `the catalytic cracking process. Y References Cited by *the xamner ,UNITED VSTATES.PATENTS Y t VVVALrHoNso D; SULLIVAN, 'Primm Examiner.

land Y said mixture intoaslurryo oil and catalyst carrying adsorbed nitrogen compounds,` andiV catalyst-free oil further reduced in nitrogen contenti,

` (4) passing said slurry to the reactionzone ofy said ree oil throughY a` secondV T he process .ot claim V1 wherein' said hydrocarbon Y 

1. A PROCESS FOR LOWERING THE NITROGEN CONTENT OF AN OIL FROM ABOVE 200 P.P.M. TO BELOW 10 P.P.M., WHICH COMPRISES: (1) PASSING A HYDROCARBON OIL CONTAINING ABOVE 200 P.P.M. NITROGEN IN NITROGEN COMPOUNDS THROUGH A FIRST CATALYTIC HYDROGENATION ZONE WHEREIN A MAJOR PORTION OF SAID NITROGEN COMPOUNDS IS REMOVED BY HYDROGENATION TO AMMONIA, AND RECOVERING LIQUID HYDROGENATED OIL BOILING BELOW ABOUT 750*F. AND REDUCED IN NITROGEN CONTENT TO BELOW 200 P.P.M. (2) CONTACTING SAID LIQUID HYDROGENATED OIL WITH A PORTION OF FRESHLY REGENERATED CRACKLINGCATALYST WITHDRAWN FROM A CATALYTIC CRACKING PROCESS, HAVING A REACTION ZONE AND A REGENERATION ZONEBETWEEN WHICH CATALYST IS CONTINUOUSLY CIRCULATED, FORMING A CATALYSTOIL MIXTURE AT CONDITIONS INCLUDING A WEIGHT RATIO OF CATALYST TO OIL BELOW 0.1, TEMPERATURE BELOW*F., AND SUFFICIENT CONTACT TIME SUCH THAT AT LEAST 10% OF THE NITROGEN COMPOUNDS IS ADSORBED ON THE CATALYST. (3) SEPARATING SAID MIXTURE INTO A SLURRY OF OIL AND CATALYST CARRYING ADSORBED NITROGEN COMPOUNDS, AND CATALYST-FREE OIL FURTHER REDUCED IN NITROGEN CONTENT, (4) PASSING SAID SLURRY TO THE REACTION ZONE OF SAID CATALYTIC CRACKING PROCESS. (5) PASSING SAID CATALYST-FREE OIL THROUGH A SECOND CATALYTIC HYDROGENATION ZONE WHEREIN, BECAUSE OF THE FOREGOING REMOVAL OF NITROGEN COMPOUNDS, THE REMAINING NITROGEN COMPOUNDS ARE SUBSTANTIALLY REMOVED BY HYDROGENATION TO AMMONIA MORE EASILY THAN IN SAID FIRST HYDROGENATION ZONE, AND RECOVERING OIL REDUCED IN NITROGEN CONTENT TO BELOW 10 P.P.M. NITROGEN. 